...Travertine is a type of calcite crystal formed when calcium carbonate (CaCO3 ) dissolved in groundwater becomes supersaturated due to the release of carbon dioxide ( CO2) into the air as a result of changes in water temperature or water evaporation, and then precipitates and forms various types of cave formations (Figure). There is a wide variety of formations in caves, including icicle-like stalactites and stalactites that hang from the ceiling of the cave, bamboo-like stalagmites that grow on the cave floor directly below, travertine columns (also called stone pillars) that are a combination of these two, limestone curtains that hang like curtains from the inward-leaning cave walls, travertine waterfalls, a type of flowing stone that falls like a waterfall on the outward-leaning cave walls, and travertine terraces, which are tiers of ridge-like pools of stone created by water flowing down a slope. There are also some interesting formations such as cave pearls formed in the dripping ponds, serpentine helictites growing from the ceilings and walls of caves as water seeps in, and floating calcite on the surface of the water. *Some of the terminology that mentions "limestone curtain" is listed below. Source | Heibonsha World Encyclopedia 2nd Edition | Information |
…石灰華travertineは地下水に溶存している炭酸カルシウムCaCO3が水温の変化や水の蒸発などのため炭酸ガスCO2の空中への放出によって過飽和となり,沈殿して方解石の結晶となったもので,それが諸種の洞穴生成物をつくる(図)。洞の天井からつらら状に垂れ下がる鍾乳管や鍾乳石,その直下の洞床に筍状に生長する石筍(せきじゆん)stalagmite,この両者が連結した石灰華柱(石柱ともいう),内傾した洞壁から幕状に垂れ下がる石灰幕limestone curtain,外傾した洞壁に滝状にかかる流華石の一種である石灰華滝,傾斜地を流れ下る水流によってつくられた畦石プールが何段にも鱗状に並んだ石灰華段丘travertine terraceなど変化に富んでいる。また,水滴の落下する池の中につくられる洞穴真珠,天井や洞壁から浸透水によって生長した曲がりくねったヘリクタイト,水面に浮かんだ浮遊カルサイトなどの興味深い生成物の見られるところもある。… ※「limestone curtain」について言及している用語解説の一部を掲載しています。 出典|株式会社平凡社世界大百科事典 第2版について | 情報 |
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